Patent EP 1 169 560 B1 describes the determination of cylinder-specific differences in a control variable of an internal combustion engine. The method makes it possible to detect cylinder-specific charging differences and to equalize them. It is further stated that the differences in the torque contributions of the individual cylinders may stem from the charging differences or the air ratio differences and thus the fuel metering. Cylinder-specific differences are determined by means of cylinder-specific air ratios and cylinder-specific torque contributions. The relationship between torque, charge and air ratio, accordingly combustion oxygen and fuel mass, is set out. A preferred development of the invention is characterised by the equalization of the cylinder-specific air ratios. Alternatively, an equalization of the cylinder-specific injection times is followed by a determination of the cylinder-specific air ratio differences. The cylinder-specific air ratio differences are determined using cylinder-specific lambda probes. Cylinder-specific charging differences are then derived. The charge can be equalized for example by fully variable actuation of the inlet and/or exhaust valves.
Publication DE 101 63 894 A1 describes a method for equalizing an amount of fuel which is injected in a cylinder-specific manner, for example the opening duration and the pressure at the injector being detected.
Patent DE 102 59 846 B3 describes a method for cylinder equalization, a throttled operation and a dethrottled operation using variable valve trains being provided. The injection amount is equalized during throttled operation of the internal combustion engine. The charge is then equalized during dethrottled operation.
Patent EP 1 448 881 B1 describes a method for equalizing the charge, in which method charge-dependent engine data are detected via sensors while the motor is running. The lift of the inlet valve is adjusted in accordance with this data in order to achieve the setpoint values for the equalization of the charge of the cylinders. Rotational non-uniformity, a lambda value in conjunction with injection parameters or knocking sensor signals are also listed as relevant engine data.